:root {
    --bg-gradient: linear-gradient(90deg, #0d6efd, #0aa2ff);
}

/* HEADER */
.demo-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 60px;
    background: #161f2d;
    z-index: 99;
    overflow: visible; /* visible để show close btn và nội dung */
    display: flex;
    align-items: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.18);
}

/* Canvas Particleground dưới container-fluid */
.demo-header .particles-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0; /* thấp hơn nội dung header */
}

/* Nội dung header */
#advanced {
    position: relative;
    z-index: 9999; /* cao hơn canvas */
    width: 100%;
}

/* LOGO */
#logo {
    height: 32px;
    width: auto;
}

/* CLOSE BTN */
#close_frame {
    position: absolute;
    right: 20px;
    bottom: -22px;
    width: 42px;
    height: 22px;
    background: #0aa2ff;
    color: #fff;
    text-align: center;
    line-height: 22px;
    border-radius: 0 0 5px 5px;
    cursor: pointer;
    box-shadow: 0 2px 5px rgba(0,0,0,0.18);
    z-index: 3; /* luôn trên hết */
}

/* TABS */
.bk-action-tab {
    display: flex;
    justify-content: center;
    gap: 15px;
}

.bk-action-tab a {
    color: rgba(255,255,255,0.85);
    font-size: 14px;
    padding: 5px 12px;
    border-radius: 6px;
    font-weight: 100!important;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 6px;
    transition: 0.25s;
    background: #2196f396;
    color: #fff;
}

.bk-action-tab a.current,
.bk-action-tab a:hover {
    background: var(--bg-gradient);
    color: #fff;
}

/* CTA BUTTON */
a.btn.btn-warning.fw-bold {
    background: var(--bg-gradient);
    color: #fff;
    border: none;
    padding: 6px 14px;
    font-weight: 100 !important;
    border-radius: 6px;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    transition: 0.25s;
}

a.btn.btn-warning.fw-bold:hover {
    opacity: 0.85;
    transform: translateY(-1px);
}

/* BODY */
#demo-body {
    margin-top: 60px;
    height: calc(100vh - 60px);
    background: #f5f5f5;
}

/* WRAPPER */
#demo_wrapper {
    width: 100%;
    height: 100%;
    background: #fff;
    overflow: hidden;
}


/* HEADER */
.demo-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 60px;
    z-index: 99;
    overflow: visible;
    display: flex;
    align-items: center;
}

/* Canvas Particleground nằm dưới container-fluid */
.demo-header .particles-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0; /* thấp hơn nội dung header */
}

a.btn-fw-bold {
    text-decoration: none;
    font-size: 19px;
    color: #ffffff;
}

/* Nội dung header container */
.demo-header .header-content {
    position: relative;
    z-index: 2; /* cao hơn canvas */
    width: 90%;
    display: flex;
    align-items: center;
}

/* CLOSE BTN */
#close_frame {
    position: absolute;
    right: 20px;
    bottom: -22px;
    width: 42px;
    height: 22px;
    background: #0aa2ff;
    color: #fff;
    text-align: center;
    line-height: 22px;
    border-radius: 0 0 5px 5px;
    cursor: pointer;
    box-shadow: 0 2px 5px rgba(0,0,0,0.18);
    z-index: 3; /* luôn trên hết */
}



/* RESPONSIVE */
@media (max-width:768px) {
    .col-3.text-end {
        flex: 0 0 auto;
        width: 100%;
    }
    .col-2 {
        flex: 0 0 auto;
        width: 49.666667%;
    }
    .col-5.text-center {
        padding: 20px;
        width: 100%;
    }
    .demo-header .header-content {
        width: 100%;
    }
    .demo-header {
        height: 192px;
    }
    #demo-body {
        margin-top: 200px;
        height: calc(100vh - 60px);
        background: #f5f5f5;
    }
}